Method of working refractory metals.



entrain STATES PATENT OFFICE. j

MARCELLO VON PIRANI, OF WTLMERSDORF, NEAR BERLIN. GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

METHOD OF WORKING REFRACTORY METALS resarse.

No Drawing.

T 0 II whom 1"! may concern Be it known that I. Mancnnm vox PIRANI, a citizen of the Italian Kingdom, residing at Vilmersdorf, near Berlin, Germany, have invented certain new and useful Improvements in Methods of \Vorking Refractory Metals, of which the following is a specification.

4 In the working of refractory metals such as tungsten, as by rolling, it is observed that the material under treatment becomes cracked after acertain amount of rolling,

the cracks formed being principally longi-.

tudinal. The formation of cracks may be to such an extent that pieces come entirely away from the material being rolled. In consequence of this phenomenon it becomes necessary to do the rolling with extreme care which increases the length of time consumed in the operation and also the cost of the" work. If great care is not. exercised a again presents a uniform character throughout. If the piece of metal so treated is again brought into the rolls it behaves like new, unrolled material.

The heating of the metal will give the best results if it is not carried on throughout the entire mass of the material rolled, but only at the place where the crack occurred and where it is desired that the metal be resintered, the character of the remaining parts of the metal will therefore be little changed. It is necessary therefore only to heat the edges and surfaces ofthe cracks whereby they will be reunited.

' One method of carrying out this invention is as follows: The piece to be rolled is heated Specification of Letters Patent.

Patented Mar. 10, 1914.

Application filed November 23, 1912. Serial No. 733,Q76.

by the electric current. It serves as one electrode and another electrode is moved over the place to be heated. By this means the effect of the heat can be closely confined and its intensityffinelyregulated. The heating may be effected in a hydrogen atmosphere in order to avoid oxidization.

The phenomenon of cracking is particularly noticeable when the rolling process lasts a long time and the material is thereby considerably cooled,- but in rolling metals in which the cooling is not a substantial fea ture'the rolling being eflected at a low temperaturesuch cracks may form but to a less extent. i

W'hat I claim as new and desire to secure by Letters Patent of the United States is 2-- 1. The process of reclaiming refractory metal which has become cracked during rolling which consists in locally heating the metal to a temperature sufficient to cause the crack to be completely and automatically eliminated merely by heating until said cracked portion becomes homogeneous, and

're-rolling said metal.

connected to the other pole of said source over said metal adiacent the fracture. and thereby raising said metal to a sufficient temperature to cause the imperfect portions to sinter together, and re-rolling said metal. In witness whereof, I have hereunto set my hand this 5th day of-November 1912.

-MARCELLO voN PIRANI.

" \Vitnesses:

HENRY HAsPER, WOLDEMAR HAUPT.

Cop!" 0! this patent may be ebtdaed' for five cents each. by addreulng the Commissioner of retenti- Washington, D. O. 

